diff --git a/runtime/ftplugin/tmux.vim b/runtime/ftplugin/tmux.vim
index ed91549..5c3461f 100644
--- a/runtime/ftplugin/tmux.vim
+++ b/runtime/ftplugin/tmux.vim
@@ -9,4 +9,7 @@
 endif
 let b:did_ftplugin = 1
 
+let b:undo_ftplugin = "setlocal comments< commentstring<"
+
+setlocal comments=:#
 setlocal commentstring=#\ %s